Device for the continuous casting and subsequent rolling of a metal from its casting heat in short steps

ABSTRACT

A method and apparatus for continuously casting metal in particular, steel rods, includes a continuous casting mold in which the rod is continuously cast and cooled to solidification as it is passed through the mold and moved through a transport path. The rod which is cast is subjected to a first set of up setting rolls and straightening rolls for reducing its cross section and for causing a stretching of the rod and a second set of high deformation rolls for further reducing the cross section and stretching the rod which is formed. The construction is characterized by an arrangement of the first acting sets of rollers at a first station to produce such a rod reduction and a rod stretching that the second acting rollers at the second station attain a maximum degree of deformation and at a faster passage rate of the rod which is cast and which therefore also requires a lower rolling force. The apparatus includes a roll stand for deforming the casting at a high reduction per pass which is preceeded by a roll stand having a roll gap which in the set in dependence upon the ratio of the casting cross section at the mold and the smallest possible rolling gap of the high deformation rollers. The construction is such that the casting cross section of the mold has a side ratio greater than one and the upsetting gap of the first roller set of approximately one and that of the high deformation stand of one or less than one. The side ratio is the relationship of the side lengths with one another.

United States Patent 1 Baumann DEVICE FOR THE CONTINUOUS CASTING ANDSUBSEQUENT ROLLING OF A METAL FROM ITS CASTING HEAT IN SHORT STEPS [75]Inventor: Hans G. Baumann,41 Duisburg,

Germany [73] Assignee: Demag Aktiengesellschaft,

Duisburg, Germany [22] Filed: Sept. 14, 1971 [Zl] Appl. No.: 180,363

Related U.S. Application Data [62] Division of Ser. No. 886,518, Dec.19, 1969.

[30] Foreign Application Priority Data Dec. 24, 1968 Germany... P l8 16849.5

[52] U.S. Cl. 164/270, 164/282 [51] Int. Cl B22d 11/12 [58] Field ofSearch..... 164/76, 82, 270, 164/282 [5 6] References Cited UNITEDSTATES PATENTS 395,684 l/l889 Baker 164/76 2,698,467 l/l955 Tarquihee etal. 164/283 X 3,317,994 5/1967 Cofer et a1 164/76 3,333,452 8/1967Sendzimir 164/76 X 3,358,358 12/1967 Jenks et al. 164/76 PrimaryExaminer-R. Spencer Annear Att0rneyMcGlew & Toren 1 July 17, 1973 [57]ABSTRACT A method and apparatus for continuously casting metal inparticular, steel rods, includes a continuous casting mold in which therod is continuously cast and cooled to solidification as it is passedthrough the mold and moved through a transport path. The rod which iscast is subjected to a first set of up setting rolls and straighteningrolls for reducing its cross section and for causing a stretching of therod and a second set of high deformation rolls for further reducing thecross section and stretching the rod which is formed. The constructionis characterized by an arrangement of the first acting sets of rollersat a first station to produce such a rod reduction and a rod stretchingthat the second acting rollers at the second station attain a maximumdegree of deformation and at a faster passage rate of the rod which iscast and which therefore also requires a lower rolling force. Theapparatus includes a roll stand for deforming the casting at a highreduction per pass which is preceeded by a roll stand having a roll gapwhich in the set in dependence upon the ratio of the casting crosssection at the mold and the smallest possible rolling gap of the highdeformation rollers. The construction is such that the casting crosssection of the mold has a side ratio greater than one and the upsettinggap of the first roller set of approximately one and that of the highdeformation stand of one or less than one. The side ratio is therelationship of the side lengths with one another.

6 Claims, 1 Drawing Figure DEVICE FOR THE CONTINUOUS CASTING ANDSUBSEQUENT ROLLING OF A METAL FROM ITS CASTING HEAT IN SHORT STEPS Thisis a division of application Ser. No. 886,518, filed Dec. 19, 1969.

SUMMARY OF THE INVENTION This invention relates in general to a methodand apparatus for continuous casting and in particular to a new anduseful method and apparatus in which the cast metal is subjected to across sectional reduction and stretching at a first station by upsettingrollers and straightening rollers and at a second station by a highdeformation roller.

The invention is concerned in particular with the favorable arrangementfor the casting and rolling of a continuous cast rod such as a steel rodwhich is formed by metal which is poured into a continuously operatingcasting mold and in which the rod is withdrawn; and during withdrawal,or directly adjacent the casting mold, the rod is subjected to coolingand solidification and thereafter to several deformation actions forreducing its cross section and causing a stretching. In moderncontinuous casting installations casting is followed by a rollingprocess which furnishes material which otherwise would have to be rolledout in billets first in an ordinary cogging mill and in many plants thisis still not a thing of the past. By rolling the billets from thecasting heat, not only a reheating of the cast material in gravitydischarge furnaces is eliminated but also for example, the work of thebillet rolling train is not required.

Efforts have been made to increase the quantity of the rolling materialwhich is obtained, This requirement results from given facts that thecasting proceeds relatively slowly as does the cooling in a continuouscasting process. The rolling device therefore operates in accordancewith the speed of the casting installation. The yield of a greaterquantity of material is therefore prevented by the naturally slow motoroperation of such installations. In continuous casting installationshaving multiple veins for the casting flow this disadvantage is reducedin accordance with a number of such casting veins. However, theinstallation expenses increases the costs of the large number of rollstands which are necessary, so that the arrangement becomes exorbitant.The technical difficulty of arranging the roll stands for each veinside-by-side appears to be insolvable. Space is lacking for such a standand for the drives which are required therefore. Large drive units arerequired depending on the stipulated forces in the economical pathreduction which is necessary. Thus for the production of a cross section70 by 70 milimeters at a casting cross section of 250 by 250 mm that astand continuous line or continuous rolling mill is necessary andneither the costs nor the complicated construction is warranted.

Such a rolling mill train for five horizontal and five vertical standswould have to be provided: for each casting vein. In the first stand, abloom of the dimensions of 250 by 250 firm would be tapped. The standsmust be arranged alternately, horizontally and vertically. The end crosssection of the rolled material is 70 by 70 mm. The output attainedthereby is 235 tons per hour or 1,680,000 tons per year and a rollingspeed of v 3.5 meters per second.

In accordance with the present invention means have been provided foravoiding the rolling on a multistrand trains and by an appropriatedifferent working method. The method at the same time increases theyield in comparison with conventional installations and also achievesadvantages of the installation design obviating the mentioneddisadvantages of spacial restriction.

In accordance with the invention, a method is proposed whereby thequantity of casting metal per unit of time is maintained at a maximum ata certain cross section formation and cooling output is arranged inconformity thereto and the metal being cast is then shaped with amaximum reduction per shaping pass. The rolling force required for theshaping of the metal is supplied in only two stations, the firstproviding a cross section reduction which causes such a stretching atthe second station, that there is attained a maximum degree ofdeformation at a faster passage rate of the casting material but at arelatively smaller rolling force. The rolling force which for optimumdeformation of the casting cannot be supplied by the high deformationmachine alone is therefore made available in preceeding station so thatthe following high deformation operation can just take place.

Another advantage of the combination of preand after-deformation residesin the upsetting of the casting, that is, in an introductorytransformation of the casting structure to a rolling texture.

The apparatus for carrying out the method is characterized by a rollstand for deforming the casting which operates to effect a highreduction per pass and which is preceeded by a roll stand whose rollinggap between rollers is set in an independent ratio in respect to thecross section of the cast metal at the casting mold and also in respectto the smallest possible rolling gap which can be attained at the highdeformation stand.

Accordingly, it is an object of the invention to provide an improvedmethod for continuously casting and rolling, from casting heat, acontinuous casting of metal, particularly steel, which comprises movingthe continuously cast rod first into association with upsetting rollmeans and straightening roll means at a first station and thereafterinto association with a high deformation roll means at a second station,the first cross sectional reduction is set to cause such a stretching ofthe rod that the second station may attain a maximum degree ofdeformation at a faster passage rate of the casting but at a relativelylow rolling force.

A further object of the invention is to provide a continuous castingapparatus which includes a first station with upsetting andstraightening rollers arranged to engage the continuous casting in acondition of casting heat, and a second station spaced from the firststation having high deformation rollers arranged with a relatively smallroll gap, and wherein the casting cross section advantageously has aside ratio greater than one and the upsetting roll gap at the firststation, a side ratio of one, and that of the at the high deformationsecond station a side ratio of one or less than one.

A further object of the invention is to provide a continuous castingdevice which is simple in design, rugged in construction, and economicalto manufacture.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which there is illustrated and described a preferredembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS The only FIGURE of the drawing is aschematic side elevational view of a continuous casting and rollingdevice constructed in accordance with the invention.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawingin particular, the invention embodied therein comprises a combinedcontinuous casting and rolling device which includes a continuouscasting ladle or distributor trough 1 from which liquid steel or othermetal flows into a continuous casting mold 2 in the form of a freelyfalling jet or in a jet guided in one or more immersion tubes. The mold2 is made to oscillate in the casting direction in a known manner inorder to bring about a favorable heat transfer between the castingmaterial and the wall plates of the mold 2. In accordance with recentunpublished proposals the liquid portion 3 of the casting 4 need notextend into the region of the horizontal but may cool off with the aidof electrical or flow caused forces (not shown) in the mannerillustrated in the drawing to cause solidification just behind the mold2. The casting 4 is supported or moved by transport or feed rolls 5 andthe movement may be entirely vertically or in a curve as indicated inthe drawing into the region of the horizontal portion 6. The resultingstructure of the casting material comprises a casting structure. Alongthe transport length of the continuous cast material the transport rolls5 cause a more or less proportional force and provisions are generallymade only to feed the casting away from the mold 2 and to transport itto the cooling section without causing any material changes in the caststructure and without internal or external damage thereto.

The cross section 8 of the casting will thus be maintained from the mold2 up to a first station 50 for reducing the cross section and stretchingthe rod. The first station 50 includes a pair of upsetting rollers 9, 9'which are mounted in a roll stand having roller pressure adjustmentmeans or presser force applying means 11. In addition, a single pair ofadditional straightening rollers 10, 10 are located on extensions 54,54' of the stand 52. The roll path 9, 9 and 10, 10 may have identical ordifferently acting diameters. The upsetting rolls 9, 9' can be pressedagainst the casting with considerable expenditure of force by means ofthe adjusting means I] in the form of a fluid pressure actuated pistonand cylinder combination which applies pressure on roller 9 to a degreewhich brings about the destruction of the casting structure in externalregions. At the same time, it is possible to drive the motors of theupsetting rolls 9, 9' and the straightening rollers 10, 10' at a speedof rotation to render the desired transmission of a ratio of compressiveand tensile stresses.

Depending on the operational situations which occur, it is possibleeither to separate, or to combine with one another, the functions ofupsetting and drawing or braking of the casting.

In the embodiment shown in the drawing the straightening rolls l0, 10'are movable toward and away from the casting but they are not rotatablydriven. The upsetting rolls 9, 9' produce besides their pressing effecta required tensile or braking effect. They are made to bear against thecasting with an upsetting force by the pressure adjustment means 11.

The casting 4 is thus pressed and brought to a certain density behindthe upsetting rolls 9, 9' and then is moved into a high deformationmachine generally designated 56. The high deformation machine 56includes mounting frames 12, 12' arranged on respective opposite sidesof the casting and each of which carries sup porting rolls l3 andworking rolls 14. An. eccentric drive 15 and its associate linkage 58provides a control for the positioning of the deformation rollers 14,14'. An upsetting rather than a stretching effect is produced on thecasting 4 but at the exit of the high deformation machine 56 theseforces work as pure stretching forces. A reaction resulting therefromwhich causes a temporary regulation of the stress ratio can readily beabsorbed by the two or more upsetting roll pairs 9, 9'. The fluctuationof quality and the homogeneous nature of the casting can thus becompensated.

The casting issues as rolling material 16 which is guided betweentransport rollers on a simple roller bed 17 and it advantageouslyconsists of a material which is already deformed to the extent that canbe passed onto the known fine steel trains or depending on therequirements intermedium steel trains.

In order to be able to operate the casting rolling method of theinvention with best success the mold 2 has a high performance castingcross section 8 with a side ratio of greater than 1 in respect to theupsetting roll gap 18. In addition the ratio of the two mentioneddistances is maintained in dependence on the roll gap 19 of the highdeformation machine 56.

A ratio of the three mentioned passages to be suggested to thespecialists should be selected, for example, that the cross section ofthe side lengths of the mold are 300 and 240 mm, the roll gap of theupsetting rolls stand 9 having a side ratio of 250 by 250 mm, while forreshaping the high deformation machine 12 side ratios of 200 by 200 mmand less as desired should be provided.

For the high deformation machine 56 there is an intermediate heatingsystem 20 or an insulation interval. A descaling device (not shown) maybe provided instead of the heating system 20 or inserted ahead of it inorder to meet the requirements for high deforming and especially toobtain a perfect material.

In an installation according to the invention the cross section of thecast material can be 300 by 240 mm which can be cast at a rate of v=1.04meters per minute and be transferred to a roll stand which fulfills thefunction of a driver. In this driver the cross section of 250 by 250 mmis obtained. Thereafter in the second operation the high deformationmachine deforms the cross section to the final cross section of by 70mm. Surprising the output of a single vein installation is about 570 kgper minute, that is, 34 tons per hour. This results in an annularproduction of I22,000 tons.

If one is to presuppose an abnormally high installation and operatingcosts (gravity discharge furnace operation will all apertaining measuresand arrange ments), a 10 stand continuous rolling mill with fivehorizontal and five vertical stands, there would indeed result, becauseof the independence from a continuous casting installation, a higherrolling speed (v velocity 3.5 meters per second). In the first stand abloom of the dimension of 250 by 250 mm would tapped. The stands wouldhave to be arranged alternately, horizontally and vertically. The finalcross section must again be taken to be 70 by 70 mm. Then there resultsan output of 235 tons per hour or 1,680,000 tons per year. Yet the costsper ton of steel is considerably higher. This is a known fact but it hasnot been possible until the present invention to solve the processproblem of optimum adaptation between continuous casting installationsand rolling arrangements.

The use of such Konti trains is thus excluded for reasons of cost andspace. But also the cooperation between a continuous castinginstallation separate from the rolling train is not economical. Aconventional continuous casting installation operates at a casting rateof 0.983 meters per minute with a casting cross section of 250 by 250mm. The output of a single vein installation is approximately 467kilograms per meter corresponding to 28 tons per hour. The annularoutput therefore is 100,000 tons of extruded steel. But even if theupsetting stand before the high deformation machine would be removed theharminizing effects of the two technological processes of casting androlling attained with the installation according to the invention and bythe method of the invention could not be achieved with success of theinventive method and apparatus. Assuring this case to occur, thecalculation is as follows: the cross section of 250 by 250 mm is runinto the high deformation machine and a casting rate of v 0.983 metersper minute and shaped to the final cross section of 70 by 70 mm. Theoutput of the signal vein installation then is 467 kilograms per minutecorresponding to the 28 tons per hour. Thus again one obtains an annularoutput of 100,000 tons which therefore is considerably below that with adriver stand (122,000 tons).

The production of the output of the casting rolling installationaccording to the invention constitutes an optimum between supply andfabrication of the casting material. It is appropriate to provide adependent ratio of the cross sectional dimensions in all stations.According to the invention the casting cross section presents a sideratio of greater than one, the upsetting rolling gap presents a ratio ofone and that of the high deformation stand of one or less than one.

During rolling, temperature variations within the range of plantpractice. At relatively large quantities and long casting times, themelt material may cool off to such a degree that influences on therolling behavior of the continuous casting are inevitable. Anothercondition results from the necessity of guiding the continuous castingcorrectly for rolling before the high deformation work cycle, that is,to supply a holding force in the casting direction. According to aspecial process the installation can be so operated that the castingtension between the high deformation stand and the upsetting stand isregulated by varying the speed of rotation of the rolls or by varyingthe working speed of the rolls of the high defonnation stand 56.

The apparatus permits the formation of the casting so that itslongitudinal sides may have a selected size in relation to the crossdimension or width to provide a related side ratio. For example, thegeometrical surface of a rectangle requires inherently a side ratiowhich only approaches one as a limit when it is the same as that of asquare, to wit 1:1. The apparatus of the invention may be constructed sothat there is a side ratio of a preselected rectangular cross-section ora square cross-section. The casting mold may have a longitudinal sidewhich is larger than the width. However, the upsetting roller nip, whichis formed by the rollers 9,9, has a through-flow opening of squarecross-section. By contrast, the nip of the deformation rollers 14,14frame is either square or rectangular. Of course, in respect to the termside ratio it is not detennined in advance where the shorter or thelonger side is to be situated. The shorter side may thus extendhorizontally or vertically.

What is claimed is:

' 1. A device for the continuous casting and subsequent rolling ofmetals from the casting heat comprising a casting mold into which themold material is poured, transport roll means adjacent said mold forwithdrawing the cast material from the mold and for moving it along afeed path, a first roller deformation station including a pairofoppositely arranged upsetting rolls bearing on opposite sides of thecasting at one location along the feed path and pressure force applyingmeans for moving first and second rollers relatively toward theworkpiece to apply an upsetting force thereto, and a second stationclosely spaced along the feed path from the said first station andincluding first and second deformation rollers arranged on respectiveopposite sides of said casting, and deformation roller positioning meansfor positioning said deformation rollers with the gap therebetween beingsufficient to deform the casting to materially reduce its cross section.

2. A device, according to claim 1, including straight-' ening rollersarranged in said first station adjacent said upsetting rollers.

3. A device, according to claim 1, wherein the gap between saidupsetting rollers is dependent on the casting cross section at said moldand also upon the smallest possible rolling gap between said deformationrollers.

4. A device, according to claim 3, wherein said casting has a side ratiogreater than one at said mold and wherein the gap between said upsettingrollers has a side ratio of one and that of the high deformation standhas a side ratio of one or less than one.

5. A device, according to claim 1, including a cooling section betweensaid transport roller means and said first station, a straighteningroller set mounted on said first station engageable with casting aftersaid upsetting rollers, and heater means disposed between said firststation and said second station.

6. A device, according to claim 1, including means associated with saidfirst station for varying the speed of said upsetting rollers and meansassociated with said second station for varying said speed of said highdeformation rollers.

4i i I t 8

1. A device for the continuous casting and subsequent rolling of metalsfrom the casting heat comprising a casting mold into which the moldmaterial is poured, transport roll means adjacent said mold forwithdrawing the cast material from the mold and for moving it along afeed path, a first roller deformation station including a pair ofoppositely arranged upsetting rolls bearing on opposite sides of thecasting at one location along the feed path and pressure force applyingmeans for moving first and second rollers relatively toward theworkpiece to apply an upsetting force thereto, and a second stationclosely spaced along the feed path from the said first station andincluding first and second deformation rollers arranged on respectiveopposite sides of said casting, and deformation roller positioning meansfor positioning said deformation rollers with the gap therebetween beingsufficient to deform the casting to materially reduce its cross section.2. A device, according to claim 1, including straightening rollersarranged in said first station adjacent said upsetting rollers.
 3. Adevice, according to claim 1, wherein the gap between said upsettingrollers is dependent on the casting cross section at said mold and alsoupon the smallest possible rolling gap between said deformation rollers.4. A device, according to claim 3, wherein said casting has a side ratiogreater than one at said mold and wherein the gap between said upsettingrollers has a side ratio of one and that of the high deformation standhas a side ratio of one or less than one.
 5. A device, according toclaim 1, including a cooling section between said transport roller meansand said first station, a straightening roller set mounted on said firststation engageable with casting after said upsetting rollers, and heatermeans disposed between said first station and said second station.
 6. Adevice, according to claim 1, including means associated with said firststation for varying the speed of said upsetting rollers and meansassociated with said second station for varying said speed of said highdeformation rollers.